I built a Mauser in 243 several years ago and I did a fair bit of research (patent office is a good place to get Browning's engineers version of the story) on the BOSS and built myself a non-brake version. Contrary to what some might tell you, it CAN do things that you can't do with just careful reloading. For example, it allows you to make your loads run as close to maximum for your rifle as is safe and then lets you tune the rifle so THOSE loads are also the best shooters ... sometimes you can get lucky and have the max loads be what your rifle likes without a BOSS, but it happens every time with a BOSS. Prairie dog sized targets at 300+ yds are non-issue for that 243.

All that being said, I wouldn't get the one with the brake for the hearing issues that accompany it ... but the non-ported versions are winners.